Difference between revisions of "Magnesium diboride"

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Latest revision as of 21:43, 21 March 2020

Magnesium diboride
Names
IUPAC name
Magnesium diboride
Preferred IUPAC name
Magnesium diboride
Other names
Magnesium boride
Properties
MgB2
Molar mass 45.93 g/mol
Appearance Dark gray solid
Odor Odorless
Density 2.57 g/cm3
Melting point 830 °C (1,530 °F; 1,100 K) (decomposes)
Boiling point (decomposes)
Insoluble
Solubility Insoluble in organic solvents
Vapor pressure ~0 mmHg
Hazards
Safety data sheet Sigma-Aldrich
Lethal dose or concentration (LD, LC):
826 mg/kg (rat, oral)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Magnesium diboride is the inorganic compound with the formula MgB2

Properties

Chemical

Magnesium diboride reacts with dilute acids to release hydrogen and a small amount of boranes, while reaction with water evolves hydrogen, without any traces of boranes. Both reactions also produce lots of heat.[1][2]

Magnesium diboride has been shown to react with KOH to produce borohydrides. The reaction is relative slow, and after 9-12 hours, the yield of the reaction is around 20%.[3]

Unlike elemental boron whose combustion is incomplete through the glassy oxide layered impeding oxygen diffusion, magnesium diboride burns completely when ignited in oxygen or in mixtures with oxidizers.

Magnesium diboride has been shown that to be a good replacement in classical decoy flares. Magnesium diboride/Teflon/Viton decoy flares display 30–60% increased spectral efficiency, Eλ (J g−1sr−1), compared to classical Magnesium/Teflon/Viton(MTV). payloads.

Physical

Magnesium diboride is a dark gray solid, insoluble in water and organic solvents.

Magnesium diboride becomes superconducting at 39 K (−234 °C), a relative high temperature for classical low-temperature superconductors.

Availability

Magnesium diboride is sold by chemical suppliers.

Preparation

The simplest synthesis involves high temperature reaction between boron and magnesium powders in an inert atmosphere. Formation begins at 650 °C; however, since magnesium metal melts at 652 °C, the reaction may involve diffusion of magnesium vapor across boron grain boundaries.

Projects

  • Demonstration of superconductivity
  • Make decoy flares

Handling

Safety

Magnesium diboride

Storage

In closed bottles, bags or boxes

Disposal

No special disposal is required, can be dumped in trash.

References

  1. https://arxiv.org/ftp/arxiv/papers/0912/0912.4906.pdf
  2. https://pubs.rsc.org/-/content/articlelanding/1935/jr/jr9350001694
  3. https://pubs.acs.org/doi/pdf/10.1021/ja01597a093

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